I hand calculated my combination of city/highway mpg's and got 14.6 but I must admit I've been hot rodding as I just did the mods last week. I'm running the 250hp on mild with XRT Pro. I've been changing the transmission settings to see which one is best for mpg's. So far I've been getting best with Low rpm shift on mild 250hp (21 mpg).

 

im gitting 25mpg on back roads and 30-35 on the high way. i have a sparten tunner, straight pipe exhaust and stage two intake

 

I'm not sure on the actual numbers but where I work stock 6.7l powerstroke f-550's get noticeably better fuel economy than a deleted and economy tuned 6.4 f-550. About evenly loaded service trucks

 

i get 14 loaded or empty , city or hwy, when i say loaded i pull a 8500 pound travel trailer , still way better than my 6.0L chevy gas burner and WAY more power.

 

Hand calculated last highway trip. Got 21.6MPG's. I'm getting around 17MPG's between city/highway. Running H&S XRT Pro on Mild 250HP tune with S&B CAI.

 

18 highway, 14 city

 

I'm getting 16.3 MPG using the H & S XRT PRO on 80 HP tune

 

Gunman, try the mild 175 and 250 tunes. I've gotten better fuel mileage on both higher tunes compared to the 80hp tune.

 

Just the 80 HP tune scare me my truck is fast enough for me the way I drive, i worry i'll get hurt

 

Truck tells me 21 but I have yet to hand calculate